A filter, as a frequency selection apparatus, is widely applied to the communications field, and in particular, to the field of radio frequency communications. In a base station, a filter is used to select a communications signal, filter out a clutter signal or an interference signal beyond a communications signal frequency, and reserve a wanted signal within a passband. With a gradually growing mass production requirement for miniaturized, high-performance, and high-power filters in the communications field, a current metal coaxial cavity filter gradually becomes incapable of satisfying the requirement due to factors such as a large volume, a limited Q value and limited power, while a dielectric filter has a relatively high Qf and power capacity, and can implement miniaturization, and therefore has an obvious advantage.
A transverse magnetic (TM) mode dielectric filter has the foregoing advantage. However, in the TM filter, sufficient contact needs to be maintained between a dielectric resonator and upper and lower surfaces of a cavity in a long term to ensure good and stable performance, and therefore, how to secure the dielectric resonator becomes a key technology. A common TM mode dielectric filter includes a cavity, a dielectric resonator disposed in the cavity, and a main cover.
In the prior art, an elastic component, such as a gasket or a thin cover, that produces an elastic acting force on the dielectric resonator is usually disposed between the dielectric resonator and the main cover, to achieve the purpose of securing the dielectric resonator. Because part of the elastic component is located within the cavity, in order to ensure electrical performance, the whole elastic component needs to be electroplated, causing a complex process and relatively high processing costs; besides, to produce an elastic force, the elastic component is bent to some degree in the cavity, causing a non-uniform current distribution and affecting the electrical performance. High-precision fitting is required between the elastic component and the cavity, between the elastic component and the main cover, and between the elastic component and a dielectric, increasing the processing and assembly difficulty.